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x86/speculation/mds: Add sysfs reporting for MDS

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commit 8a4b06d391 upstream.

Add the sysfs reporting file for MDS. It exposes the vulnerability and
mitigation state similar to the existing files for the other speculative
hardware vulnerabilities.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jon Masters <jcm@redhat.com>
Tested-by: Jon Masters <jcm@redhat.com>
[bwh: Backported to 4.9: test x86_hyper instead of using hypervisor_is_type()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Thomas Gleixner
2019-02-18 22:51:43 +01:00
committed by Greg Kroah-Hartman
parent 4e722ae314
commit ba08d562b0
4 changed files with 39 additions and 0 deletions
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1
Documentation/ABI/testing/sysfs-devices-system-cpu
View File

@@ -357,6 +357,7 @@ What: /sys/devices/system/cpu/vulnerabilities
/sys/devices/system/cpu/vulnerabilities/spectre_v2
/sys/devices/system/cpu/vulnerabilities/spec_store_bypass
/sys/devices/system/cpu/vulnerabilities/l1tf
/sys/devices/system/cpu/vulnerabilities/mds
Date: January 2018
Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
Description: Information about CPU vulnerabilities

28
arch/x86/kernel/cpu/bugs.c
View File

@@ -25,6 +25,7 @@
#include <asm/vmx.h>
#include <asm/paravirt.h>
#include <asm/alternative.h>
#include <asm/hypervisor.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/intel-family.h>
@@ -1161,6 +1162,24 @@ static ssize_t l1tf_show_state(char *buf)
}
#endif
static ssize_t mds_show_state(char *buf)
{
#ifdef CONFIG_HYPERVISOR_GUEST
if (x86_hyper) {
return sprintf(buf, "%s; SMT Host state unknown\n",
mds_strings[mds_mitigation]);
}
#endif
if (boot_cpu_has(X86_BUG_MSBDS_ONLY)) {
return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],
sched_smt_active() ? "mitigated" : "disabled");
}
return sprintf(buf, "%s; SMT %s\n", mds_strings[mds_mitigation],
sched_smt_active() ? "vulnerable" : "disabled");
}
static char *stibp_state(void)
{
if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
@@ -1222,6 +1241,10 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
if (boot_cpu_has(X86_FEATURE_L1TF_PTEINV))
return l1tf_show_state(buf);
break;
case X86_BUG_MDS:
return mds_show_state(buf);
default:
break;
}
@@ -1253,4 +1276,9 @@ ssize_t cpu_show_l1tf(struct device *dev, struct device_attribute *attr, char *b
{
return cpu_show_common(dev, attr, buf, X86_BUG_L1TF);
}
ssize_t cpu_show_mds(struct device *dev, struct device_attribute *attr, char *buf)
{
return cpu_show_common(dev, attr, buf, X86_BUG_MDS);
}
#endif

8
drivers/base/cpu.c
View File

@@ -531,11 +531,18 @@ ssize_t __weak cpu_show_l1tf(struct device *dev,
return sprintf(buf, "Not affected\n");
}
ssize_t __weak cpu_show_mds(struct device *dev,
struct device_attribute *attr, char *buf)
{
return sprintf(buf, "Not affected\n");
}
static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL);
static DEVICE_ATTR(l1tf, 0444, cpu_show_l1tf, NULL);
static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL);
static struct attribute *cpu_root_vulnerabilities_attrs[] = {
&dev_attr_meltdown.attr,
@@ -543,6 +550,7 @@ static struct attribute *cpu_root_vulnerabilities_attrs[] = {
&dev_attr_spectre_v2.attr,
&dev_attr_spec_store_bypass.attr,
&dev_attr_l1tf.attr,
&dev_attr_mds.attr,
NULL
};

2
include/linux/cpu.h
View File

@@ -54,6 +54,8 @@ extern ssize_t cpu_show_spec_store_bypass(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_l1tf(struct device *dev,
struct device_attribute *attr, char *buf);
extern ssize_t cpu_show_mds(struct device *dev,
struct device_attribute *attr, char *buf);
extern __printf(4, 5)
struct device *cpu_device_create(struct device *parent, void *drvdata,